1. Draw stereochemical formulas
for all the possible stereoisomers of the following
compounds. Label pairs of enantiomers and meso compounds.
(a) CH3CHBrCH2CH(CH3)NH2
(b) CH3CHBrCH2CH2CH(CH3)Br
(c) CH3(CHOH)3CH3
(d) 1,4-dicyanocyclohexane
2. (a) What is the lowest molecular
weight alkane that is chiral?
Draw stereochemical formulas of the enantiomers and specify each as R or S. (b) What is the other alkane with the
same molecular weight that is also chiral? Give
structures for the enantiomers and designate as R or
S. (c) Draw the structure of the lowest molecular weight alkane
that is meso.
3. In a study of the chlorination of propane, four products
(A, B, C, and D) of formula C3H6Cl2 were
separated by gas chromatography. Further chlorination of A, B, C, and D gave 1,
2, 3, and 3 trichloroproducts, respectively. Use of chiral shift reagents in NMR experiments showed that only C
could be obtained in optically active form. Identify A, B, C, and D.
4. Identify the relationship between the following pairs of
molecules, e.g., conformational enantiomers, configurational diasteromers,
identical, etc. Provide a structural drawing for each molecule.
(a) (R,R)-2,3-dibromobutane and
(S,S)-2,3-dibromobutane (Fischer projection)
(b) (+)-tartaric acid and meso-tartaric
acid (Fischer projection)
(c) 1,3-diaxial-dimethylcyclohexane
and 1,3-diequatorial-dimethylcyclohexane (chair conformation)
(d) (3R,5S)-3,5-dihydroxyheptane
and (3S,5R)-3,5-dihydroxyheptane
(e) cis-1-ethyl-2-methylcyclohexane and trans-1-ethyl-2-methylcyclohexane
5. The specific rotation of (+)-tartaric acid is +12.0°. What is the optical purity, enantiomeric excess, and percentage composition of a mixture of (+)- and (–)-tartaric acid with a specific rotation of 9.8°?
6.
(a) Draw a structure with formula C4H4F2Cl2 that is not optically active and does not have a plane of symmetry in any conformation.
(b) Draw three enantiomeric pairs with formula C5H8.